/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */

/**
 * @file
 * ICMP - Internet Control Message Protocol
 *
 */

/* Some ICMP messages should be passed to the transport protocols. This
   is not implemented. */

#include "lwip/opt.h"

#if LWIP_IPV4 && LWIP_ICMP		/* don't build if not configured for use in lwipopts.h */

#include "lwip/icmp.h"
#include "lwip/inet_chksum.h"
#include "lwip/ip.h"
#include "lwip/def.h"
#include "lwip/stats.h"

#include <string.h>

#ifdef LWIP_HOOK_FILENAME
#include LWIP_HOOK_FILENAME
#endif

/** Small optimization: set to 0 if incoming PBUF_POOL pbuf always can be
 * used to modify and send a response packet (and to 1 if this is not the case,
 * e.g. when link header is stripped of when receiving) */
#ifndef LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
#define LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN 1
#endif							/* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */

/* The amount of data from the original packet to return in a dest-unreachable */
#define ICMP_DEST_UNREACH_DATASIZE 8

static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code);

/**
 * Processes ICMP input packets, called from ip_input().
 *
 * Currently only processes icmp echo requests and sends
 * out the echo response.
 *
 * @param p the icmp echo request packet, p->payload pointing to the ip header
 * @param inp the netif on which this packet was received
 */
void icmp_input(struct pbuf *p, struct netif *inp)
{
	u8_t type;
#ifdef LWIP_DEBUG
	u8_t code;
#endif							/* LWIP_DEBUG */
	struct icmp_echo_hdr *iecho;
	const struct ip_hdr *iphdr_in;
	u16_t hlen;
	const ip4_addr_t *src;

	ICMP_STATS_INC(icmp.recv);
	MIB2_STATS_INC(mib2.icmpinmsgs);

	iphdr_in = ip4_current_header();
	hlen = IPH_HL(iphdr_in) * 4;
	if (hlen < IP_HLEN) {
		LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short IP header (%" S16_F " bytes) received\n", hlen));
		goto lenerr;
	}
	if (p->len < sizeof(u16_t) * 2) {
		LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: short ICMP (%" U16_F " bytes) received\n", p->tot_len));
		goto lenerr;
	}

	type = *((u8_t *) p->payload);
#ifdef LWIP_DEBUG
	code = *(((u8_t *) p->payload) + 1);
#endif							/* LWIP_DEBUG */
	switch (type) {
	case ICMP_ER:
		/* This is OK, echo reply might have been parsed by a raw PCB
		   (as obviously, an echo request has been sent, too). */
		MIB2_STATS_INC(mib2.icmpinechoreps);
		break;
	case ICMP_ECHO:
		MIB2_STATS_INC(mib2.icmpinechos);
		src = ip4_current_dest_addr();
		/* multicast destination address? */
		if (ip4_addr_ismulticast(ip4_current_dest_addr())) {
#if LWIP_MULTICAST_PING4
			/* For multicast, use address of receiving interface as source address */
			src = netif_ip4_addr(inp);
#else							/* LWIP_MULTICAST_PING4 */
			LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to multicast pings\n"));
			goto icmperr;
#endif							/* LWIP_MULTICAST_PING4 */
		}
		/* broadcast destination address? */
		if (ip4_addr_isbroadcast(ip4_current_dest_addr(), ip_current_netif())) {
#if LWIP_BROADCAST_PING
			/* For broadcast, use address of receiving interface as source address */
			src = netif_ip4_addr(inp);
#else							/* LWIP_BROADCAST_PING */
			LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: Not echoing to broadcast pings\n"));
			goto icmperr;
#endif							/* LWIP_BROADCAST_PING */
		}
		LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ping\n"));
		if (p->tot_len < sizeof(struct icmp_echo_hdr)) {
			LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: bad ICMP echo received\n"));
			goto lenerr;
		}
#if CHECKSUM_CHECK_ICMP
		IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_ICMP) {
			if (inet_chksum_pbuf(p) != 0) {
				LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: checksum failed for received ICMP echo\n"));
				pbuf_free(p);
				ICMP_STATS_INC(icmp.chkerr);
				MIB2_STATS_INC(mib2.icmpinerrors);
				return;
			}
		}
#endif
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
		if (pbuf_header(p, (s16_t)(hlen + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN))) {
			/* p is not big enough to contain link headers
			 * allocate a new one and copy p into it
			 */
			struct pbuf *r;
			/* allocate new packet buffer with space for link headers */
			r = pbuf_alloc(PBUF_LINK, p->tot_len + hlen, PBUF_RAM);
			if (r == NULL) {
				LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
				goto icmperr;
			}
			if (r->len < hlen + sizeof(struct icmp_echo_hdr)) {
				LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("first pbuf cannot hold the ICMP header"));
				pbuf_free(r);
				goto icmperr;
			}
			/* copy the ip header */
			MEMCPY(r->payload, iphdr_in, hlen);
			/* switch r->payload back to icmp header (cannot fail) */
			if (pbuf_header(r, (s16_t) - hlen)) {
				LWIP_ASSERT("icmp_input: moving r->payload to icmp header failed\n", 0);
				pbuf_free(r);
				goto icmperr;
			}
			/* copy the rest of the packet without ip header */
			if (pbuf_copy(r, p) != ERR_OK) {
				LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("icmp_input: copying to new pbuf failed"));
				pbuf_free(r);
				goto icmperr;
			}
			/* free the original p */
			pbuf_free(p);
			/* we now have an identical copy of p that has room for link headers */
			p = r;
		} else {
			/* restore p->payload to point to icmp header (cannot fail) */
			if (pbuf_header(p, -(s16_t)(hlen + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN))) {
				LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
				goto icmperr;
			}
		}
#endif							/* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN */
		/* At this point, all checks are OK. */
		/* We generate an answer by switching the dest and src ip addresses,
		 * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
		iecho = (struct icmp_echo_hdr *)p->payload;
		if (pbuf_header(p, (s16_t) hlen)) {
			LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Can't move over header in packet"));
		} else {
			err_t ret;
			struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
			ip4_addr_copy(iphdr->src, *src);
			ip4_addr_copy(iphdr->dest, *ip4_current_src_addr());
			ICMPH_TYPE_SET(iecho, ICMP_ER);
#if CHECKSUM_GEN_ICMP
			IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_GEN_ICMP) {
				/* adjust the checksum */
				if (iecho->chksum > PP_HTONS(0xffffU - (ICMP_ECHO << 8))) {
					iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
				} else {
					iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
				}
			}
#if LWIP_CHECKSUM_CTRL_PER_NETIF
			else {
				iecho->chksum = 0;
			}
#endif							/* LWIP_CHECKSUM_CTRL_PER_NETIF */
#else							/* CHECKSUM_GEN_ICMP */
			iecho->chksum = 0;
#endif							/* CHECKSUM_GEN_ICMP */

			/* Set the correct TTL and recalculate the header checksum. */
			IPH_TTL_SET(iphdr, ICMP_TTL);
			IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
			IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_GEN_IP) {
				IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, hlen));
			}
#endif							/* CHECKSUM_GEN_IP */

			ICMP_STATS_INC(icmp.xmit);
			/* increase number of messages attempted to send */
			MIB2_STATS_INC(mib2.icmpoutmsgs);
			/* increase number of echo replies attempted to send */
			MIB2_STATS_INC(mib2.icmpoutechoreps);

			/* send an ICMP packet */
			ret = ip4_output_if(p, src, LWIP_IP_HDRINCL, ICMP_TTL, 0, IP_PROTO_ICMP, inp);
			if (ret != ERR_OK) {
				LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ip_output_if returned an error: %s\n", lwip_strerr(ret)));
			}
		}
		break;
	default:
		if (type == ICMP_DUR) {
			MIB2_STATS_INC(mib2.icmpindestunreachs);
		} else if (type == ICMP_TE) {
			MIB2_STATS_INC(mib2.icmpintimeexcds);
		} else if (type == ICMP_PP) {
			MIB2_STATS_INC(mib2.icmpinparmprobs);
		} else if (type == ICMP_SQ) {
			MIB2_STATS_INC(mib2.icmpinsrcquenchs);
		} else if (type == ICMP_RD) {
			MIB2_STATS_INC(mib2.icmpinredirects);
		} else if (type == ICMP_TS) {
			MIB2_STATS_INC(mib2.icmpintimestamps);
		} else if (type == ICMP_TSR) {
			MIB2_STATS_INC(mib2.icmpintimestampreps);
		} else if (type == ICMP_AM) {
			MIB2_STATS_INC(mib2.icmpinaddrmasks);
		} else if (type == ICMP_AMR) {
			MIB2_STATS_INC(mib2.icmpinaddrmaskreps);
		}
		LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: ICMP type %" S16_F " code %" S16_F " not supported.\n", (s16_t) type, (s16_t) code));
		ICMP_STATS_INC(icmp.proterr);
		ICMP_STATS_INC(icmp.drop);
	}
	pbuf_free(p);
	return;
lenerr:
	pbuf_free(p);
	ICMP_STATS_INC(icmp.lenerr);
	MIB2_STATS_INC(mib2.icmpinerrors);
	return;
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN || !LWIP_MULTICAST_PING4 || !LWIP_BROADCAST_PING
icmperr:
	pbuf_free(p);
	ICMP_STATS_INC(icmp.err);
	MIB2_STATS_INC(mib2.icmpinerrors);
	return;
#endif							/* LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN || !LWIP_MULTICAST_PING4 || !LWIP_BROADCAST_PING */
}

/**
 * Send an icmp 'destination unreachable' packet, called from ip_input() if
 * the transport layer protocol is unknown and from udp_input() if the local
 * port is not bound.
 *
 * @param p the input packet for which the 'unreachable' should be sent,
 *          p->payload pointing to the IP header
 * @param t type of the 'unreachable' packet
 */
void icmp_dest_unreach(struct pbuf *p, enum icmp_dur_type t)
{
	MIB2_STATS_INC(mib2.icmpoutdestunreachs);
	icmp_send_response(p, ICMP_DUR, t);
}

#if IP_FORWARD || IP_REASSEMBLY
/**
 * Send a 'time exceeded' packet, called from ip_forward() if TTL is 0.
 *
 * @param p the input packet for which the 'time exceeded' should be sent,
 *          p->payload pointing to the IP header
 * @param t type of the 'time exceeded' packet
 */
void icmp_time_exceeded(struct pbuf *p, enum icmp_te_type t)
{
	MIB2_STATS_INC(mib2.icmpouttimeexcds);
	icmp_send_response(p, ICMP_TE, t);
}

#endif							/* IP_FORWARD || IP_REASSEMBLY */

/**
 * Send an icmp packet in response to an incoming packet.
 *
 * @param p the input packet for which the 'unreachable' should be sent,
 *          p->payload pointing to the IP header
 * @param type Type of the ICMP header
 * @param code Code of the ICMP header
 */
static void icmp_send_response(struct pbuf *p, u8_t type, u8_t code)
{
	struct pbuf *q;
	struct ip_hdr *iphdr;
	/* we can use the echo header here */
	struct icmp_echo_hdr *icmphdr;
	ip4_addr_t iphdr_src;
	struct netif *netif;

	/* increase number of messages attempted to send */
	MIB2_STATS_INC(mib2.icmpoutmsgs);

	/* ICMP header + IP header + 8 bytes of data */
	q = pbuf_alloc(PBUF_IP, sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE, PBUF_RAM);
	if (q == NULL) {
		LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMP packet.\n"));
		MIB2_STATS_INC(mib2.icmpouterrors);
		return;
	}
	LWIP_ASSERT("check that first pbuf can hold icmp message", (q->len >= (sizeof(struct icmp_echo_hdr) + IP_HLEN + ICMP_DEST_UNREACH_DATASIZE)));

	iphdr = (struct ip_hdr *)p->payload;
	LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded from "));
	ip4_addr_debug_print_val(ICMP_DEBUG, iphdr->src);
	LWIP_DEBUGF(ICMP_DEBUG, (" to "));
	ip4_addr_debug_print_val(ICMP_DEBUG, iphdr->dest);
	LWIP_DEBUGF(ICMP_DEBUG, ("\n"));

	icmphdr = (struct icmp_echo_hdr *)q->payload;
	icmphdr->type = type;
	icmphdr->code = code;
	icmphdr->id = 0;
	icmphdr->seqno = 0;

	/* copy fields from original packet */
	SMEMCPY((u8_t *) q->payload + sizeof(struct icmp_echo_hdr), (u8_t *) p->payload, IP_HLEN + ICMP_DEST_UNREACH_DATASIZE);

	ip4_addr_copy(iphdr_src, iphdr->src);
#ifdef LWIP_HOOK_IP4_ROUTE_SRC
	{
		ip4_addr_t iphdr_dst;
		ip4_addr_copy(iphdr_dst, iphdr->dest);
		netif = ip4_route_src(&iphdr_src, &iphdr_dst);
	}
#else
	netif = ip4_route(&iphdr_src);
#endif
	if (netif != NULL) {
		/* calculate checksum */
		icmphdr->chksum = 0;
#if CHECKSUM_GEN_ICMP
		IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_ICMP) {
			icmphdr->chksum = inet_chksum(icmphdr, q->len);
		}
#endif
		ICMP_STATS_INC(icmp.xmit);
		ip4_output_if(q, NULL, &iphdr_src, ICMP_TTL, 0, IP_PROTO_ICMP, netif);
	}
	pbuf_free(q);
}

#endif							/* LWIP_ICMP */
